There are sound systems available which provide a listener with a full sound experience such that the reproduced sound appears to come to the listener as though it were being played "live" in the presence of the listener.
The DOLBY (a trademark of Dolby Labs) surround systems are typical of such systems where a listener can enjoy a full range of sound spread out in a three dimensional pattern around the listener. One major drawback to such systems is that they require more than the traditional two (left and right) speakers. Typically, these systems require at least three (the third being a center speaker for speech and other "centered" sounds) and usually also require two rear speakers. For maximum enjoyment at least one sub-woofer is also required so that the listener can hear and perhaps even feel sounds in the range from 100 Hz and below. In addition, most existing surround systems provide the same sound to both rear speakers. An example of a system in which the rear speakers have the same sound signals is Dolby ProLogic.
New systems are coming on the market whereby an improvement has been made in that the rear speakers actually receive different sound signals thereby creating a left and right effect to the rear of the listener. An example of a prior art system in which the rear speakers have different sound signals is Dolby Digital (AC3).
The above-described systems assume a very import parameter that simply is not true in most situations. The assumption is that listeners of the sound system will have the five (or more) speakers necessary to take advantage of the full range of the sound systems. Most people simply can not afford to, or choose not to, install in their listening area the number (and quality) of speakers necessary for enjoyment of these full sound systems. Also, most people have more than one location from which they wish to listen to music, the TV, etc., and the need for five (or more) speakers limits their listening options considerably.
Furthermore, computer enthusiasts are precluded from taking advantage of the surround sound systems described above where use of more than two speakers is awkward.
Accordingly, a need exists in the art for a system which can accept the five sound signal inputs (left front, right front, center front, left rear and right rear) for a surround sound system and to convert those signal inputs for presentation to left and right front speakers while still maintaining the full sound experience for the listener.
A further need exists in the art for such a system in which the sound signal inputs for the rear speakers can be either the same or different for each speaker.